If you title your CC "DDLists" and put this in the ThisDocument Module of the VB Project, it will do what your describe when the user exits the CC.
Code:
Option Explicit
Private Sub Document_ContentControlOnExit(ByVal ContentControl As ContentControl, Cancel As Boolean)
Dim oRng As Range
Select Case ContentControl.Title
Case "DDList"
Set oRng = ContentControl.Range.Paragraphs(1).Range
oRng.Collapse wdCollapseEnd
oRng.InsertAfter ContentControl.Range.Text & vbCr
End Select
lbl_Exit:
Exit Sub
End Sub